1. Field of the Invention
The invention relates generally to electrical switching apparatus and, more particularly, to interlock assemblies for safety switches.
2. Background Information
Safety switches are used in electrical power distribution systems in order to electrically isolate a load or a portion of a power circuit.
Typically, safety switches include an operating mechanism housed within an enclosure, such as a sheet metal cabinet. The operating mechanism includes an operating handle, which typically has either a single-throw configuration, in which the operating handle is operable between two positions (e.g., an ON position and an OFF position), or a double-throw configuration, in which the operating handle has three positions (e.g., a first ON position, a central OFF position, and a second ON position). A more detailed description of the components of safety switches and the operation thereof is provided, for example, in U.S. Pat. No. 6,373,009.
Safety switches are sometimes employed as mechanisms for disconnecting and transferring power that is provided, for example, from a primary power source (e.g., utility service) to a secondary or back-up source (e.g., a generator), for example, in the event that power from the primary power source is interrupted (e.g., a power outage). Such safety switches are sometimes of the aforementioned double-throw variety, with the first ON position corresponding to power being provided to a residence or commercial facility by the primary power source. Following the interruption in primary power, the operating handle can be moved to the second ON position in order that power is supplied to the residence or commercial facility by the generator. More specifically, the safety switch typically includes a number of electrical connectors for receiving conductors (e.g., electrical cables) that extend from the generator. Thus, in a typical power outage scenario, the safety switch operating handle is first turned to the OFF position, and the electrical cables are connected from the generator to the electrical connectors of the safety switch. Connecting the cables when the operating handle is in the OFF position ensures that the safety switch is not energized when the connection is being made, and thereby avoids potential injury. Then, once the electrical cables are safely connected, the operating handle is then turned to the second ON position, in order to source power from the generator.
It is desirable to restore power as quickly as possible in response to a power outage. Accordingly, the electrical connectors of the safety switch are preferably structured to facilitate for the relatively quick and easy connection of the generator cables. To meet this need, prior proposals have employed quick-connect type electrical connectors such as, for example and without limitation, Cam-Lock® and Posi-Lok™ connectors. Cam-Lock® and Posi-Lok™ connectors are available, for example, from Crouse-Hinds Molded Products of LaGrange, N.C. However, known safety switch designs have positioned such quick-connect connectors in an exposed (e.g., outside the safety switch enclosure) or readily accessible position. This presents a serious safety concern.
It is, therefore, desirable to provide a safety switch having improved safety features. Specifically, it is desirable to resist the possibility of unintentionally connecting the generator cables when the safety switch is energized (e.g., the operating handle is in the first ON position or the second ON position).
There is, therefore, room for improvement in electrical switching apparatus, such as safety switches.